[billkinney]

I bought a rebuilt 400 from a machine shop with a 3 year warranty. It ran well for 400 miles. I put it in storage for 3 months. When I started it up it broke a valve, piston and cylinder. The shop asked what kind of fuel I used. "93 no ethanol for 100 miles and 2 tanks of avgas 6 months before". He said the avgas dried out the valves and another $4000 would fix it. What's your opinion?
Bill

[Joe's Garage]

The gas could certainly go sour in three months, but I doubt it would do the amount of damage you describe.

I've let cars sit for over a year and they just ran crappy until I put fresh gasoline into them.

[Navy Horn 16]

He's full of ****. You can't "dry out" metal, and it doesn't have any moisture requirement to stay solid. I wouldn't run a full tank of 100LL mostly because you don't need that much octane in a street motor, but it won't damage the engine. The worst you will get is some lead fouling on your plugs and send some of that extra money out your tailpipe in unburnt gas if your compression ratio isn't high enough.

He's drying to duck out of his warranty.

[Navy Horn 16]

Originally Posted by Joe's Garage

The gas could certainly go sour in three months, but I doubt it would do the amount of damage you describe.

I've let cars sit for over a year and they just ran crappy until I put fresh gasoline into them.

Ethanol is what goes bad in modern fuels. Avgas is way more stable than today's pump gas. It has to be.

[TinInjun]

Ask the machines shop what kind of special alien metals they use in aircraft piston engines, and how they manage to stay together. His explanation is a bunch of BS.

[TedRamAirII]

I wonder if a valve/guide was too tight and stayed OPEN! Ask him to show you the disclaimer in his "warranty" about using gasoline thats better than it needs to be.

[694.1]

A steaming pant-load. And FYI, I am told that 100LL has a shelf life of 5 YEARS. One gallon a tank full should be plenty to protect valves.

[billkinney]

Originally Posted by 694.1

A steaming pant-load. And FYI, I am told that 100LL has a shelf life of 5 YEARS. One gallon a tank full should be plenty to protect valves.

The engine has 10.5 pistons and a guess hp of 400. Does the fuel lubricate the valves? I will not pay to rebuild a motor with 400 miles on it.














































i

[STEELCITYFIREBIRD]

So what broke, intake or ex valve?
Where did it break?
Where is the stem, still in the guide or did the spring pull it out?
Did the engine run or did it break @ startup after prolonged storage? Break at high(er) rpm??

Some pictures may provide a more probable accurate autopsy.

So many variables as to what may have happened.
Was the cause/blame based on inspection of the damaged part/s or merely talk?

[JSPONT]

Gas would have nothing to do with a valve breaking. Did you pull it apart?? Didi he? If it is not apart and he told you that he must have x ray vision to see what happened.
Take photos when pulling it apart, and be there and take pictures if he is pulling it apart.

[PunchT37]

Originally Posted by 694.1

A steaming pant-load. And FYI, I am told that 100LL has a shelf life of 5 YEARS. One gallon a tank full should be plenty to protect valves.

I used that gas for a long time in a 455 with 62 heads. Good gas. We had some in a Harley motorcycle. It sat for many years. Started and ran fine with that gas. Did not have the "old gas" smell.

[Goatracer1]

Ran Avgas when racing my 421 for 10 years with no problems. The guy just doesn't want to pay up.

[hurryinhoosier62]

Originally Posted by Navy Horn 16

He's full of ****. You can't "dry out" metal, and it doesn't have any moisture requirement to stay solid. I wouldn't run a full tank of 100LL mostly because you don't need that much octane in a street motor, but it won't damage the engine. The worst you will get is some lead fouling on your plugs and send some of that extra money out your tailpipe in unburnt gas if your compression ratio isn't high enough.

He's drying to duck out of his warranty.

I concur. I’ve spent most of my adult life maintaining aircraft recip engines. The material aircraft valves are constructed of isn’t terribly different from what quality automotive valves are constructed of.

[hurryinhoosier62]

Originally Posted by TinInjun

Ask the machines shop what kind of special alien metals they use in aircraft piston engines, and how they manage to stay together. His explanation is a bunch of BS.

LMAO!

[Tom Vaught]

My son has thousands of hours in Twin Engine aircraft engines that run 100LL gasoline. As was posted the gas is very stable.

The guy has no clue what he is talking about and was just grasping at straws (using the info you gave him) to try to back out of his poor workmanship and warranty on the engine.

Aviation Engines typically can go 200 hours or in car miles (35,000) assuming a speed of 175 mph on average with basically just oil changes and adding fuel to the tanks. AND they do not have valve issues.

Tom V.

[Tim Corcoran]

I have used 100LL in my street car with no problems ever. I also know guys who have ran it for years with no issues. I think the guy is just making an excuse to not make good on the warranty. The 100LL is actually better for the engine than the unleaded at the pump because it has lead in it to cushion the valve seats.

[billkinney]

#2 exhaust valve broke at the bottom of the stem. springs pulled the stem up. On start up it didn't reach 500 rpms, spit, sputter and pow. it was purring like a kitten when I parked it. Also, all of the water jackets were rusty. I used antifreeze from day 1.

[Tom Vaught]

Did the machine shop[ just "tune-up" your engine parts, Valve Job, block work, etc or were there a lot of new parts installed?

Tom V.

[billkinney]

I was told it was all new parts

[grivera]

Originally Posted by billkinney

The engine has 10.5 pistons...

Did the builder say this? No such thing in a Pontiac as the overall chamber size and piston valve reliefs determine compression.

Listen to the advice you've gotten here. Either the builder is incompetent or he is BS'ing you so he doesn't have to honor the warranty.